WDDM driver causes blank screen on login

After upgrading to VirtualBox 4.1.0 and upgrading guest box additions, using the WDDM driver (answering no to the 3D question), Windows gives me a blank screen after logging in. I am using Windows 7 x86. I was previously using VirtualBox 4.0.12 (as well as other previous versions) and associated guest addition 3D drivers (previous versions being installed in safe mode of course).

I can get past the problem by saving the state and then restarting the VM. In this case, I get a crash message from Desktop Window Manager and the graphics are rather strange. I'm not sure if the strangeness of the graphics is related to the WDDM driver or the fact that I saved the state and then restored it.

Change History

I confirm. Ubuntu 11.04 amd64 host, Win7-64 guest.
After the latest VBox update to 4.1.2 I installed the Aero support from guest additions. After that, as standard user I get a black screen. As admin I can work almost as usual, but IE9 is blank/black as well. Other browsers run.
I tried both other possibilities, i. e. installed no 3D driver at all and in safe mode classic 3D driver. Much worse, Windows did not start at all.

No 3D-support installed and 3D-support DISABLED in VBOX: (repeat attempt)
Uninstall GA. I think I did a reboot here. Then reinstall without WDDM. Reboot guest.
Black screen when guest login should appear.

So at first it seemed weird and like some settings were reversed. However, because of the final attempt were it suddenly started working with no-wddm + no-3d again, I suspect that what was needed was a complete shutdown of the VM after the GA was installed/upgraded. Not just a guest reboot.